The present invention refers to an electricity meter, preferably intended for measuring, registering and reading consumer's power consumption and/or energy consumption. In presently established power distribution networks, producers in utilities all over the country transfer electricity from power generating plants to the consumers. A great deal of the energy is distributed to low voltage subscribers, as for example domestic or residential users. Usually every consumer has at least one conventional electro-mechanical electricity meter intended for registration of the consumers' consumption of electrical energy during a predetermined time period. Conventional mechanical electricity meters mainly comprise a rotating disc, the speed of rotation of which is influenced by the consumers' momentary power consumption. The rotary movement is mechanically transferred to a counting device, which registers the energy consumption, for instance, in units of kWh. This conventional electricity meter must of course be manually read at regularly recurring time intervals by meter inspectors employed by the producer. The electrical energy which is produced by the power generating plants is usually supplied to the distributing network in large areas where the networks are interconnected and is, in this way, transferred to the consumer.
Depending on the type of power generating plant that produces the electrical energy, the cost of production will fluctuate. In the conventional power distribution network the momentary production cost, or the so called short time marginal cost, cannot directly influence the debiting for the amount of energy the consumer has consumed; rather, the fee for the electrical energy is primarily gathered through fixed tariffs mainly based on the long term marginal cost. A load on the distributing network is gathered by needs and the load varies heavily during day and night. Great variations occur between day and night, between different seasons like summer and winter. Because of bad correlation between the cost for production and the tariff, there is no stimulus for the consumer to change pattern of behavior concerning energy consumption and therefore the irregular load on the distribution network remains.
This, in combination with the fact that a conventional electricity meter does not show the consumer's power consumption in easy readable form, the consumer has no opportunity to observe momentary electricity consumption and its cost. The effect of conservation efforts accomplished by the consumer cannot be identified and this would, of course, not influence the consumer's conservation efforts.
To the electric power producer the peak load of the energy consumption determines how new electric power stations should be constructed. The production capability must be dimensioned for the largest possible load peaks to keep the voltage on the distribution network at a constant level. If these peak loads could be distributed over time, the dimension of the electric power station could be set to a lower peak power level and be built for a lower cost which, of course, influences the energy tariff. Also the distribution network, such as transmission wires, transformers, and the like, could be dimensioned for smaller power levels and be used at more uniform loads which is naturally more economical, both for the power producer and for the country.
It is therefore desirable to make the consumer aware of his momentary power consumption and make it possible to change the tariff dependent on whether the production cost for electric energy goes up or down. By providing every consumer with information about their energy consumption and putting this in relation to the existing tariff the consumers could be more aware about their costs. This could in turn influence the consumer to transfer at least a part of their energy consumption to periods during the day and night, or during the year, when energy production cost is lower. This could, for example, result in consumers heating their houses or flats partly during the night. Use of washing machines, dish washers, dryers, and the like, could also preferably be moved to periods when the load on the distribution network and the energy tariff is lower. If the consumer could always be aware of his momentary power consumption and its cost, the consumer's propensity to save would increase. In the long run this could bring about lower costs for new electric power stations and for new distribution networks for electric energy transmission.
Electricity meters adapted for indication of consumers' momentary power consumptions, and/or for indicating used energy by, for instance, monetary units, are previously known (for example U.S. Pat. No. 3,683,343). This invention concerns an energy meter system and has a number of disadvantages. Among others, the electricity meters, mainly of mechanical configuration, include a number of retardation coils, which heavily limit the number of values or tariffs possible to transmit on the distribution network for use in costs calculations. The reason is the bandwidth required to transmit the various tariffs, because every rate value consists of one code or signal superimposed on the electricity distribution network. This brings about that only a few tariffs, with relatively large differences among them, can be used. Another disadvantage is that the consumers have opportunity to read their present energy consumption on this electricity meter, because the different tariff signals provided to the meter influence the speed gear and make it rotate with another speed when the energy tariff is changed. The accumulated energy cost shown on the electricity meter is therefore not an adequate value on the consumers accumulated energy consumption, counted in kWh, which naturaly is completely unsatisfying from the consumer's point of view, because the accuracy of the registered consumption is difficult to control. This electricity meter is also more expensive to manufacture, even in long series, because of its fine mechanical construction, and its reliability could be questioned.